In one aspect, the present invention provides an active pixel sensor array with optimized matching between pixels and strength and frequency of incoming signals such as photons absorbed. The array comprises multiple pixels of individual geometry corresponds to spatial location. Each pixel full-well is adjustable via modifiable pixel conversion gain while maintaining pixel linearity. Furthermore each pixel internally stores multiple of extremely high frequency samples. Variable pixel geometry per row is very advantageous for Echelle spectrograph, where pixel heights are aligned with the spectrograph “order separator” where the resolution changes. In combination with variable geometry, externally adjustable full-well provides for superior spectral line separation in spectroscopy applications. In one embodiment multiple time windows with intermittent resets are stored within each pixel. This feature allows for the detection of extreme high frequency consecutive events without saturation such as may be the case with LIBS (Laser Induced Breakdown Spectroscopy).
Legal claims defining the scope of protection, as filed with the USPTO.
1. A pixel cell array for an imager, comprising: a plurality of first pixel cells of a first geometrical shape; and a plurality of second pixel cells of a second geometrical shape, wherein each of the pixel cells comprises: a radiation sensor; an amplifier coupled to an output of the radiation sensor; a reset switch coupled to the output of the radiation sensor and an input of the amplifier; a plurality of conversion gain units coupled to the output of the radiation sensor and the input of the amplifier; a plurality of control units coupled to the plurality of conversion gain units; a plurality of memory units coupled to an output of the amplifier; a row select switch coupled to outputs of the memory units; and a column output line coupled to the row select switch.
2. The pixel cell array of claim 1 , wherein first geometrical shape has a different shape than the second geometrical shape.
3. The pixel cell array of claim 1 , wherein first geometrical shape has a different area than the second geometrical shape.
4. The pixel cell array of claim 1 , wherein the amplifier comprises a source follower transistor.
5. The pixel cell array of claim 1 , wherein the amplifier comprises an operational amplifier.
6. The pixel cell array of claim 1 , wherein the switches comprise transistors.
7. The pixel cell array of claim 1 , wherein the radiation sensor comprises a photodiode.
8. The pixel cell array of claim 1 , wherein the radiation sensor comprises a photogate.
9. The pixel cell array of claim 1 , wherein the radiation sensor comprises a bipolar junction transistor (BJT).
10. The pixel cell array of claim 1 , wherein the first pixel cells and the second pixel cells are in alternating columns of the array.
11. The pixel cell array of claim 10 , wherein the second pixel cells are an L-shape and have a larger area than the first pixel cells.
12. The pixel cell array of claim 11 , wherein the first pixel cells have a rectangular or square shape.
13. The pixel cell array of claim 1 , wherein the first pixel cells are along a first row, and the second pixel cells are along a second row, wherein the first pixel cells have an area less than the second pixel cells.
14. The pixel cell array of claim 13 , further comprising a plurality of pixel cells in succeeding rows, each row of pixel cells having an area less than a subsequent row of pixel cells.
15. A method of operating a pixel cell array sensor, the pixel cell array having a plurality of pixel cells with plurality of shapes, the pixel cells having a radiation sensor coupled to an amplifier and to a reset switch, a plurality of conversion gain units coupled to a plurality of control units, a plurality of memory units coupled to the amplifier, a row select switch coupled between the memory units and an output line, the method comprising: (a) clearing the memory units; (b) for each memory unit, setting a reset voltage on the row reset switch; increasing the voltage on an input node of the conversion gain units in proportion to a photon-generated charge by the radiation sensor; and sampling outputs of the conversion gain units into the memory unit; (c) activating the row select switch; (d) for each memory unit, selecting a memory unit; and then increasing a voltage on an output of a column in proportion to the voltage stored in the column of the memory unit.
16. The method of claim 15 , further comprising selecting conversion gains for the conversion gain units prior to (b).
17. The method of claim 15 , further comprising selecting conversion gains for the conversion gain units for each memory unit prior to setting the reset voltage for each memory unit.
18. The method of claim 15 , wherein at least two of the pixel cells have different full wells based on a selection of conversion gain for a corresponding pixel cell.
19. The method of claim 15 , wherein the pixel cells comprise a plurality of first pixel cells and a plurality of second pixel cells in alternating columns of the array.
20. The method of claim 19 , wherein the second pixel cells are an L-shape and have a larger area than the first pixel cells.
21. The method of claim 20 , wherein the first pixel cells have a rectangular or square shape.
22. The method of claim 21 , wherein each row of pixel cells has an area less than a subsequent row of pixel cells.
23. A method of operating a pixel cell array sensor, the pixel cell array having a plurality of pixel cells with a plurality of shapes, the pixel cells having a radiation sensor coupled to an amplifier and to a reset switch, a plurality of conversion gain units coupled to a plurality of control units, a plurality of memory units coupled to the amplifier, a row select switch coupled between the memory units and an output line, the method comprising: selecting conversion gains for the conversion gain units; setting a reset voltage on the reset switch; clearing the memory units; increasing a voltage on an input node of the conversion gain units in proportion to a photon-generated charge by the radiation sensor; for each memory unit, sampling outputs of the conversion gain units into a memory unit; activating the row select switch; and for each memory unit, selecting a memory unit and increasing a voltage on an output of a column in proportion to the voltage stored in the column of the memory unit.
24. The method of claim 23 , wherein the pixel cells comprise a plurality of first pixel cells and a plurality of second pixel cells, wherein first pixel cells have a geometrical shape different than the second pixel cells.
25. The method of claim 23 , wherein the pixel cells comprise a plurality of first pixel cells and a plurality of second pixel cells, wherein first pixel cells have areas different than the second pixel cells.
26. The method of claim 23 , wherein each row of pixel cells has an area less than a subsequent row of pixel cells.
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December 15, 2010
March 26, 2013
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